Return of SpaceX cargo ship delayed by rough seas

SpaceX's Dragon cargo ship was originally scheduled to return from the International Space Station on Wednesday, but rough seas have delayed the trip until Saturday.

Both NASA and SpaceX said there is nothing wrong with the spacecraft. Officials simply don't want to risk damage to the science experiments stored inside the Dragon capsule.

The Pacific Ocean splashdown site is currently characterized by high winds, large swells and choppy waters.

"It's really the weather," Gary Jordan, a spokesperson at NASA's Johnson Space Center in Houston, told Space.com. "There were looking and the sea states and waves."

The Dragon capsule is already loaded up and ready to go. In addition to refuse and unneeded equipment, the capsule is loaded up with scientific samples and a variety of partially completed experiments. Most of the samples, including plants, insects and human tissue, are frozen, but a few are alive.

"Mice living on the station have been transferred to specialized habitats in Dragon," NASA announced in a blog update. "They will be studied on Earth to observe how their bones and muscles have changed during their stay in microgravity."

Also aboard the capsule are the results of a drug study, an experiment designed to test the effects of microgravity on the synthesis and deployment of five different therapeutic compounds.

"This investigation determines the feasibility of developing improved pharmaceuticals in microgravity using a new method to test the metabolic impacts of drug compounds," NASA said earlier this year. "This could lead to more effective, less expensive drugs."